Method of tobacco sucker control



United States Patent 14 Claims. (CI. 7178) This application is adivision of Ser. No. 337,100, filed Ian. 10, 1964.

A non-exclusive, irrevocable, royalty-free license in the inventionherein described, throughout the world for all purposes of the UnitedStates Government, with the power to grant sublicenses for suchpurposes, is hereby granted to the Government of the United States ofAmerica.

This invention relates to a method for controlling the growth of suckersin tobacco plants. More particularly, it relates to the use of certainfatty acid derivatives to control sucker growth in tobacco plants. H

'An established process for tobacco farmers is to remove the stem apex,including flowers and some top leaves, near the stage of plant maturityto stimulate the development of the remaining leaves and to obtaindesirable physical and chemical properties for the best utility. Thisprocess is commonly known as topping. After such an operation, axillarybuds, or suckers, start to develop, and these suckers have to becontinuously removed to achieve the purpose of topping. Usually theremoval of suckers is carried out by hand, which is a laboribus andtime-consuming process. Certain chemical growthcontrol agents have beensuggested; but while some of these provide adequate inhibition of suckerdevelopment and are in commercial use, other metabolic changes areinduced which are considered undesirable in tobacco quality. Inaddition, there has been some question of undesirable residues of theseagents in the leaf tissue.

It is an object of this invention to provide a method and compositionswhich can successfully control sucker growth without any adverse effectson the tobacco leaves and on the resultant products made therefrom.Another object is to provide compositions effective to control suckergrowth which will not introduce any undesirable foreign residues intothe tobacco leaf tissues. Other obthe upper portions of decapitated, ortopped, tobacco plants, or to plants on which the flower buds have newlyformed, will accomplish the foregoing objectives. More having newlyformed flower buds, a lower alkyl ester of a fatty acid, mixtures ofsuch esters, or a mixture of such an ester with a synthetic growthcontrol substance.

It has been found that the lower alkyl (particularly the methyl) estersof C to C saturated and unsaturated fatty acids are useful for thepurposes of this invention, the methyl esters of the C to C fatty acidsbeing particularly effective in concentrations as low as 5%.

In practicing the invention it is merely necessary to prepare an aqueousemulsion of the desired ester and spray it on the decapitated plant oronto the newly formed flower buds. Any suitable emulsifying agent can beused in preparing the composition.

Without being bound by the explanation of the mechanism of the action ofthe esters, it appears that the meristematic and differentiating cellsof axillary buds are particularly, the present invention involves thediscovery that, when the lower alkyl esters, especially the methylesters of both saturated and unsaturated fatty acids, superior suckercontrol is achieved without at the same time introducing undesirableresidues, inducing undesirable metabolic changes, or otherwise producingresults which are considered in the industry to lower the quality of thetobacco. It was further discovered that certain synthetic growthregulators, notably, isopropyl-N-(3-chlorophenyl) carbamate, whichordinarily cause leaf deformation when applied in amounts effective tocontrol suckers, can now be used in amounts as low as onetenth of thoseformerly required, when mixed with the fatty acid alkyl esters.Effective control is thus achieved without leaf deformation. In additionmixtures of esters can be used.

Thus, the present invention comprises a method of controlling the growthof suckers in tobacco plants by applying to the tops of decapitatedplants, or to plants destroyed when contacted by the fatty acid esters,but cells in advanced stage of maturity are not affected. Thus, theesters do not impair the mature tobacco leaves while they destroy theaxillary buds. In addition, because the axillary buds are destroyed oncontact, the esters themselves do not take part in the metabolism of theplant and do not enter the tissues of the plant so that the treatmentdoes not cause any changes other than those normally occurring duringhand suckering.

Furthermore, many fatty acids, including myristic, pentadecanoic,pentadecenoic, palmitic, palmitoleic, stearic, oleic, linoleic, andlinolenic, are naturally present in tobacco leaves, while palmitic,stearic, oleic, and linoleic acids are among the acids naturally presentin tobacco seeds. Thus, the application of fatty acid esters accordingto this invention will not introduce compounds foreign to thecomposition of the tobacco.

In order that the invention may be better understood, reference is madeto the following examples. It will be recognized, however, that theseexamples are illustrative only and that those skilled in the art will beable to prepare other compositions on the basis of the disclosurewithout departing from the spirit of the invention.

' Example 1 Example 2 A mixture of methyl laurate with methyl myristatewas prepared in five fomulations containing 50%, 70%,

%, and 96% laurate and 48%, 28%, 18%, 8%, and

2% myristate, respectively. 2 ml. of the mixtures of methyl esters plus.8 ml. of Tween-20, and 40 ml. of water,

-were emulsified and sprayed onto the topped tobacco plant. This gavesucker inhibition of 100%, 99%, 100%, and 99%, respectively.

Example 3 Use 2 ml. of methyl ester mixture of 55% caprylate'and 40%caprate and .8 ml. of Tween-20 and 40 ml. of Water, emulsified andsprayed onto the topped tobacco plants,

gave 100% sucker inhibition.

Example 4 An emulsion of 2 ml. of methyl ester of pelargonic acid .plus.8 ml. of Tween-20 and 40 ml. of Water sprayed onto 3 4 the top of thetopped tobacco plant gave 98% sucker The mixture, after being emulsifiedwas sprayed onto inhibition. topped tobacco plants, and was effective inpreventing Example 5 the growth of suckers.

i In Table 1, below, are listed the data on sixteen experi- 2 I111- Of &mlXturB 48% methyl lallfath, 17% Y IS- ments using the methyl esters ofvarious commercially tate, 8% caprylate, 7% caprate, 9% palmltat and 7%obtained fatty acids. The percentages set forth in each oleate,emulsified with .8 ml. of Tween-20 and 0 ml. of horizontal linerepresent the amounts of the component Water, and sprayed onto thetopped tobacco plant gave acids in each commercial acid. Thus, forexample, in 100% sucker inhibition. Treatment No. 1, the caprylic acidused consisted of The following examples illustrate the synergisticefiect 10 90% caprylic acid itself, 7% caproic acid (C and 3% producedwhen the fatty acid esters are mixed with syncapric a id (C Columns11-13 set forth the four thetic growth inhibitors which, if used alonein effective types of tobacco plant which were treated, while the lastconcentrations, cause leaf deformities and changes in column states theaverage inhibition obtained with each tobacco quality. variety.

TABLE 1.PERCENT OF SUCKER INHIBITION OF FOUR TYPES OF TOBACCO [Averageof two crops, 50 plants each crop] T t Percent of various fatty acidmethyl esters in mixture Percent Sucker Inhibition (3 wks. altertopping) rea merit No. Cap- Cap- Cap- Lau- Myrls- Palmi- Stear- OleateLino- Maryland Burley Conn.

roate ry ate r rate bate tate ate l8 leate Cm Catterton Hicks 21Broadleaf Average Ca Ca C10 12 14 10 C18 79 92 73 88 83 97 96 92 98 96100 99 100 96 99 83 85 94 89 92 98 82 94 92 89 9O 72 78 82 9O 9O 68 7982 95 89 86 88 89 96 86 87 52 8O 96 94 95 70 88 20 84 66 69 23 58 56 9090 100 59 85 1 2 ml. of ester mixture emulsified in 40 ml. of waterapplied per plant. 2 Applied twice with one week intervals.

Example 6 Table 2 below sets forth data on four treatments 1n- Emulsionswere prepared as described above, using 1 vo g mlXtllfeS of methyl p yand CIPC, as Well and 2 ml. portions of methyl caprate (95%) and 20 andas one uslng free 10-undeceno1c acid and one using meth- 40 mg. of CIPC,isopropyl-N-(3-chlorophenyl) carbayl pelargonate.

TABLE 2.TESTS WITH MATERIALS DERIVED FROM OR MIXED WITH FATTY ACIDSPercent Sucker Inhibition (3 wks. after topping) Treatment No.Composition Maryland Hicks Burley 21 Connecticut Average CattertonBroadleaf Methyl caprylate 1 1111. plus 20 mg. CIPC 2 98 98 Methylcaprylate 1 ml. plus 40 mg. CIPC Z 100 91 100 96 96 Methyl eaprylate 2ml. plus 20 mg. CIPC 2 100 100 Methyl caprylate 2 ml. plus 40 mg. CIPC 2100 100 94 98 IO-undecenoic acid CnHzoOz 100 99 100 100 100 Methylpelargonate 4 CH3(CHZ)7COOOHQ 98 100 93 98 97 1 1 ml. of esteremulsified in 40 ml. of water.

2 CIPC Isopropyl -N-(3-ch1orophenyl) carbamate. 3 2 ml. of esteremulsified in 40 ml. of water.

4 2 ml. emulsified in 40 ml. of water.

mate. When sprayed on decapitated tobacco plants, 96

to 100% sucker inhibition was achieved. The amounts of 60 Table 3 setsforth data on experiments carried out on CIPC were One-tenth and h, p hy, the field-grown Maryland tobacco for the purpose of comfimOllIltS 9:that agent normally requlred to obtam eflec' paring the results obtainedaccording to the present intive inhibltlonvention with those usingmaleic hydrazide, an inhibitor f? 5 currently in widespread use forinhibiting growth of From 50 to 100 parts per mllllOll of CIPC wereadded Suckers to 40 ml. portions of a 5% methyl caprate emulsionprepared as previously described These were sprayed onto In addition tothe percent of sucker 1nh1b1t1on, field tobacco plants having newlyformed flower buds. Both appearance was rated based on general Plant pphh the flower buds and axillary buds were destroyed. By leaf pp leafdamage, other a i sthis procedure it was possible to prevent blossomingand Field appearance is rated from 1 to 5, 5 being the highest toeliminate the suckering process. rating. The product of percent ofsucker inhibition and Example 8 field appearance is called Desirabilityindex. Results A mixture was prepared of 1 ml. of undecenoic acid fromTable 3 show that maleic hydrazide is ranked 5 in (C I-1 0 0.8 m1. ofTween-20, and 40 ml. of water. atest of 8 materials.

TABLE 3.-DESIRABILITY EVALUATION OF SOME FATTY ACID TREATMENTS INCOMPARISON WITH MALEIC HYDRAZIDE (FIELD-GROWN MARYLAND TOBACCO) l Thecomposition of each treatment number is described in Table 1. 2 Averageof four replications. 3 Commercially used growth control agent (forpurposes of comparison).

I claim:

1. A method of inhibiting the growth of suckers in tobacco plants whichcomprises applying to topped tobacco plants an amount of a lower alkylester of a C to C fatty acid effective to achieve at least about 47%inhibi tion of sucker growth.

2. A method of inhibiting the growth of suckers in tobacco plants whichcomprises applying to topped tobacco plants an amount of an aqueousemulsion of a member of the group consisting of a lower alkyl ester of aC to C fatty acid and mixtures of such esters efiective to achieve atleast about 47% inhibition of sucker growth.

3. The method of claim 2 wherein the lower alkyl ester is the methylester.

4. The method of claim 2 wherein the ester is methyl caproate.

5. The method of claim 2 wherein the ester is methyl caprylate.

6. The method of claim 2 wherein the ester is methyl caprate.

7. The method of claim 2 wherein the ester is methyl laurate.

8. The method of claim 2 wherein the ester is methyl myristate.

9. The method of claim 2 wherein the ester is methyl palmitate.

10. The method of claim 2 wherein the ester is methyl stearate.

11. The method of claim 2 wherein the ester is methyl oleate.

12. The method of claim 2 wherein the ester is methyl linoleate.

13. The method of claim 2 wherein the ester is methyl pelargonate.

14. A method of inhibiting the growth of suckers in tobacco plants whichcomprises applying to topped tobacco plants an amount of an aqueousemulsion of IO-undecenoic acid eflective to achieve inhibition of suckergrowth.

References Cited UNITED STATES PATENTS 2,772,152 11/1956 Emond et al.71-2.7 X 3,223,517 12/ 1965 Abramitis et al. 71-2.7

OTHER REFERENCES Tso et al.: Chemical Abstracts, vol. 59, column 8064(e), 1963.

LEWIS GOTIS, Primary Examiner.

JAMES O. THOMAS, IR., Examiner.

1. A METHOD OF INHIBITING THE GROWTH OF SUCKERS IN TOBACCO PLANTS WHICHCOMPRISES APPLYING TO TOPPED TABACCO PLANTS AN AMOUNT OF A LOWER ALKYLESTER OF A C6 TO C18 FATTY ACID EFFECTIVE TO ACHIEVE AT LEAST ABOUT 47%INHIBITION OF SUCKER GROWTH.